[ Post a Response | San Gorgonio Backcountry Bulletin Board ]
Posted by FIGHT ON on August 17, 2009, 18:42:50, in reply to "Re: Benchmark on SG peak? "
208.127.88.205
The San Andreas fault is the border between two tectonic plates—the North American Plate and Pacific Plate. Los Angeles is located on the Pacific Plate, and San Francisco is on the North American Plate. In a few million years, the two geographic areas will be right next to each other because the western side of the fault (the Pacific Plate) is moving northward with respect to the rest of the state. The fault is moving at about 2 centimeters (just under an inch) per year.
Check this one out.
http://www.data.scec.org/fault_index/sanandre.html
--Previous Message--
: I spoke with two guys from U of A up
: there on Sunday morning. They said
: the sensor can be calibrated to
: detect motion down to a millimeter.
: From preliminary findings, it looks
: like San G is going northwest at
: about 16 millimeters per year,
: whereas San J is going north at
: about 18 millimeters per year. At
: least, that's roughly how I remember
: it. I would have expected San G to
: either be stationary or moving
: south. One of the guys said the
: fault system (and you are right,
: it's the San Andreas) is very
: complex in this area, and at this
: point not well understood. They
: were going to move the sensor over
: to San Jacinto, I believe, and keep
: it up there for three days as well.
: Apparently, it increases in accuracy
: with repeated honing of its position
: in relation to the satellites, so
: millimeter precision takes a while.
:
: Incidentally, the marker is still
: there, exactly where it's always
: been, and the sensor was in place
: over the marker, actually
: pinpointing its location by having a
: sharp pointed arm stick into a small
: dimple in the marker.
:
: z
:
: --Previous Message--
: Was I supposed to leave that round
: thing on the top?
:
: It's the San Andreas Fault.
:
: http://geology.com/san-andreas-fault/
:
: Geologists believe that the total
: accumulated displacement from
: earthquakes and creep is at least
: 350 miles along the San Andreas
: fault since it came into being about
: 15-20 million years ago. Studies of
: a segment of the fault between Tejon
: Pass and the Salton Sea revealed
: geologically similar terranes on
: opposite sides of the fault now
: separated by 150 miles, and some
: crustal blocks may have moved
: through more than 20 degrees of
: latitude.
:
: --Previous Message--
: I hope there's not too much relative
: motion! Isn't that the San Jacinto
: Fault that runs between the two
: peaks? Weren't they recently
: reporting about swarms of
: micro-earthquakes on the fault, and
: wondering if they were possibly
: useful in the prediction of major
: earthquakes?
:
: z
:
: --Previous Message--
: My mistake, it is University of Az.
: However, according to the abstract
: on the website
:
:
:
: (http://www.geo.arizona.edu/pdf/GeoDaze_2009.pdf)
: the GPS unit is directly over the
: benchmark. There is another unit on
: the peak of Mt. San Jacinto as well.
: Students are studying the relative
: movement of the 2 peaks.
: Very interesting!
:
: --Previous Message--
: There was a standard brass benchmark
: up there, but the boulder it was on
: rolled over. There is a very small
: black-colored one up there (about
: 1.5" across) just southwest of
: the old phone box used as a
: register. I tried to get a picture
: of it this past June but its too
: small to focus on without a macro
: lens.
:
:
:
: --Previous Message--
: I was just up there on Thursday, and
: also couldn't find the marker.
:
: There was a spot on one of the
: boulders that looked like it had a
: bolt, and two holes that looked
: about 4-5 fingers apart. Is that
: where one HAD BEEN? Did someone
: STEAL the summit marker?
:
: The equipment at the summit, I
: thought it said University of
: Arizona and someone was there
: checking on it when we at the summit
: but we didn't get a chance to ask
: any questions (we were recovering in
: one of the wind shelters at the time
: ;-)
:
: -az-
:
: --Previous Message--
: Just at S.G. Couldn't find a
: benchmark! I heard there's supposed
: to be 2! Does anyone know what the
: instrumentation (UC Santa Cruz)is
: about?
:
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